Most heating appliences used to have those cords.

I remember "electric fires" with them.

Most irons still have them, actually are they required to have them?

They are very poor at withstanding mechanical ware and tend to fray where the cord rubs over the ironing board after a number of years.

Ours goes a step further 5 core + steam [Linked Image]

Live, Neutral + Earth, two smaller signaling cables to control the steam and a tube carrying steam to the iron from the steam generator base unit [Linked Image]